Apparatus for electrical testing of a substrate having a plurality of terminals

ABSTRACT

According to one aspect of the invention apparatus is provided for electrical testing of a substrate having a plurality of terminals. The apparatus includes a frame, a probe card, a translation device, an alignment device, and a holder. The probe card includes a probe card backing member and a plurality of probes extending from the probe card backing member and is secured to the frame. The translation device is secured to the frame. The alignment device is located on the translation device. The holder is capable of holding a substrate and is secured to the alignment device. The alignment device is operable to cause alignment movement of the holder past the probe card so that selected ones of the terminals are brought into alignment with selected ones of the probes. The translation device is operable to cause translational movement, transverse to the alignment movement, of the alignment device with the holder towards the probe card. A respective one of the terminals is so brought into contact with a respective contact region of a respective one of the probes.

[0001] Priority is claimed from U.S. Provisional Patent Application No.60/143,196 filed on Jul. 9, 1999.

BACKGROUND OF THE INVENTION

[0002] 1). Field of the Invention

[0003] This invention relates to an apparatus for electrical testing ofa substrate having a plurality of terminals.

[0004] 2). Discussion of Related Art

[0005] Substrates such as wafers or other arrays of packaged electronicsdevices often have active circuits formed within them. Terminals areformed on the substrates to which electrical contact can be made forpurposes of testing the circuits before final assembly. Probe cards areused for making electrical contact with the terminals. A probe cardincludes a plurality of probes which are brought into contact with theterminals. An electrical tester is connected to the probes. Electricalsignals can be transmitted from the electrical tester thorough theprobes and the terminals to the electrical circuits, or signals can besent from the circuits through the terminals and probes to theelectrical tester.

[0006] In order to make proper contact between the probes and theterminals, the substrate and terminals have to be brought into alignmentwith one another both rotationally and positionally, and then be movedcloser to one another. A force has been exercised between the probe cardand the substrate to ensure proper contact between contact regions ofthe probes and the terminals.

[0007]FIG. 4 illustrates one apparatus that can be used for aligning andprobing of a substrate includes a frame 110, a probe card 112, ahorizontal alignment stage 114, and a vertical translation stage 116.The probe card 112 is secured in the top of the frame 110. The alignmentstage 114 is located on the base of the frame 110 and the translationstage 116 is located on the alignment stage 114. The alignment stage 114can be moved in horizontal directions and the translation stage 116 canbe moved relative to the alignment stage 114 in a vertical direction.The translation stage 116 generally includes a screw 118 with a holder120 located on top of the screw 118 for securing a substrate to.

[0008] A problem with the apparatus of FIG. 4 is that the screw 118moves together with the alignment stage 114 in horizontal directions. Acenter axis of the screw 118 is thus movable relative to a center pointof the probe card 112. When the translation stage 116 is moved in anupwardly direction so that the substrate makes contact with the probecard 112, a moment 122 is created because of misalignment of a forcecreated by the probe card 112 with respect to a center axis of the screw118. The moment 122 has a tendency to topple the translation stage. As aconsequence, the screw 118 has to be of a relatively bulky design to beable to counteract the moment that is created.

SUMMARY OF THE INVENTION

[0009] According to one aspect of the invention apparatus is providedfor electrical testing of a substrate having a plurality of terminals.The apparatus includes a frame, a probe card, a translation device, analignment device, and a holder. The probe card includes a probe cardbacking member and a plurality of probes extending from the probe cardbacking member and is secured to the frame. The translation device issecured to the frame. The alignment device is located on the translationdevice. The holder is capable of holding a substrate and is secured tothe alignment device. The alignment device is operable to causealignment movement of the holder past the probe card so that selectedones of the terminals are brought into alignment with selected ones ofthe probes. The translation device is operable to cause translationalmovement, transverse to the alignment movement, of the alignment devicewith the holder towards the probe card. A respective one of theterminals is so brought into contact with a respective contact region ofa respective one of the probes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The invention is further described by way of example withreference to accompanying drawings wherein:

[0011]FIG. 1 is a side view illustrating apparatus, according to anembodiment of the invention, for electrical testing of a substratehaving a plurality of terminals;

[0012]FIG. 2 is a perspective view of components of the apparatus ofFIG. 1;

[0013]FIG. 3a is a perspective view of a substrate and terminals whichhave to be brought into contact with one another using the apparatus ofFIG. 1;

[0014]FIG. 3b is a view similar to FIG. 3a after the substrate isrotated;

[0015]FIG. 3c is a view similar to FIG. 3b after the substrate is movedso that each terminal is located directly below each probe;

[0016]FIG. 3d is a view similar to FIG. 3c after the substrate is movedin an upward direction so that each terminal contacts a respectivecontact region of a respective one of the probes; and

[0017]FIG. 4 is a side view illustrating apparatus for electricaltesting of a substrate according to the prior art.

DETAILED DESCRIPTION OF THE INVENTION

[0018]FIG. 1 of the accompanying drawings illustrates an apparatus 10,according to an embodiment of the invention, for electrical testing of asubstrate having a plurality of terminals. The apparatus 10 includes aframe 12, a probe card 14, a translation device 16, an alignment device18, and a holder 20.

[0019] The frame 12 includes a base 22, posts 24, and an overhead probecard support structure 26. The base 22 is located on a horizontalsurface, the posts 24 are secured to the base 22 and extend upwardlytherefrom, and the overheard probe card support structure 26 is securedto and between upper ends of the posts 24.

[0020] The probe card 14 includes a probe card backing member 28 and aplurality of probes 30 secured to the probe card backing member 28. Theprobe card backing member 28 is secured to the overhead probe cardsupport structure 26 in a position wherein the probes 30 extenddownwardly from the probe card backing member 28.

[0021] The translation device 16 includes a translation stage 34, guidepins 36, guide bearings 38, and a load applicator 40.

[0022] Each guide pin 36 is secured to the base 22 and extends upwardlytherefrom. Each guide bearing 38 is secured to the translation stage 34.Each guide bearing 38 is located over a respective guide pin 36. Thetranslation stage 34 is moveable in an upward and downward translationdirection 42 while the guide pins 36 slide within the guide bearings 38and confine the movement of the translation stage 34 to the translationdirection 42.

[0023] The load applicator 40 includes a small electric motor 46, ascrew 48, a nut 50, and connector beams 52. The motor 46 is secured tothe base 22 and the screw 48 is connected to the motor 46 so that thescrew 48 is rotated by the motor 46. The nut 50 is located on the screw48. The nut 50 and the screw 48 have complementary threaded formations.The nut 50 is connected to the translation stage 34 by the connectorbeams 52. Rotation of the screw 48 causes rotation of the threadedformation on the screw 48 within the threaded formation within the nut50. The nut 50 is non-rotationally secured to the translation stage 34and moves up or down in the translation direction 42 when the screw 48rotates. Movement of the nut 50 is transferred through the connectorbeams 52 to the translation stage 34 so that the translation stage 34moves in the translation direction 42 when the screw 48 rotates. Thescrew 48 can be rotated in opposite directions to cause either upward ordownward movement of the translation stage 34 in the translationdirection 42.

[0024] Reference is also made to FIG. 2 which illustrates the alignmentdevice 18 located on the translation stage 34 in more detail. Thealignment device 18 includes a Sawyer motor 56 which is used forhorizontal alignment, and a rotation stage 58 that is used forrotational alignment.

[0025] The Sawyer motor 56 includes a Sawyer platen 60 located on thetranslation stage 34 and a Sawyer forcer 62 located on the Sawyer platen60. Sawyer motors are well known in the art and have been used in X-Ystages for semiconductor wafer probers, such as wafer probers ofElectgroglas, Inc., of Santa Clara, Calif. The Sawyer forcer 62 rides onan air bearing located between the Sawyer forcer 62 and the Sawyerplaten 60 and serves as an alignment stage for a substrate. Apositioning actuator is provided in the form of magnets andelectgromagnets 66 located on the Sawyer platen 60 and the Sawyer forcer62. The magnets and electromagnets 66 provide a connection between theSawyer platen 60 and the Sawyer forcer 62 so that, when operated, theSawyer forcer 62 is moved in transverse alignment directions 68 and 70over the Sawyer platen 60. Other details of Sawyer motors will beevident to one skilled in the art.

[0026] The rotation stage 58 is located on the Sawyer forcer 62 and isrotatable in a direction 72. An electric motor 74 rotates the rotationstage 58 in the direction 72.

[0027] The operation of the apparatus 10 is now described with referenceto FIG. 1, FIG. 2, and FIG. 3a to FIG. 3d. A substrate 76 having aplurality of terminals 78 located thereon is located on the holder 20.The holder 20 may for example be a vacuum chuck which retains thesubstrate 76. As shown in FIG. 3a, the terminals 78 and the probes 30may initially be misaligned. As shown in FIG. 3b, the substrate 76 istypically rotated in a direction 72 by rotating the rotation stage 58.The substrate 76 is thus rotated about an axis transverse to a plane ofthe substrate 76. The probes 30 may then still not be located over theterminals 76, although the terminals 76 and the probes 30 may berotationally aligned in the sense that the probes 30 are located in rowsthat are parallel to rows of the terminals 78.

[0028] As shown in FIG. 3c, the substrate 76 is then moved in adirection 70 and a direction 68 by moving the Sawyer forcer 62 over theSawyer platen 60. Each one of the probes 30 is then located over arespective one of the terminals 78.

[0029] The electric motor 46 is then operated so that the translationstage 34, the Sawyer motor 56, the rotation stage 58, the holder 20, andthe substrate 76 move in a direction 42 towards the probe card 14. Eachone of the terminals 78 is thereby brought into contact with a contactregion 80 of a respective one of the probes 30. In order to ensure thatproper contact is made, the substrate 76 is moved further into thedirection 42, thereby deflecting the probes 30. Because of thedeflection, a force is exercised by the probes 30 on the substrates 76.The force is counteracted by the screw 48.

[0030] It should be noted that the screw 48 is at all times locateddirectly below the probe card 14. The force exercised by the probes 30is downward and directly aligned with a center axis of the screw 48.Should the force not be aligned with a center axis of the screw 48, amoment would be created which will tend to topple the translation stage34. However, because the force of the probes 30 is aligned with a centeraxis of the screw 48, no moment is created. It should also be noted thatalthough no moment is created because the probe card 14 is locateddirectly above the screw 48, positional alignment as shown in FIG. 3c isstill allowed for because of the use of an alignment stage in the formof the Sawyer forcer 62 on top of the translation stage 34.Substantially the same advantages can be accomplished with a slightoffset in alignment.

[0031] A prior art device wherein a moment in created due tomisalignment of a translation screw with respect to a probe cardrequires a much larger translation screw and motor. The largertranslation screw is necessary to counteract the moment created in thepresent embodiment. By contrast, a very small motor 46 and translationscrew 48 are used in the embodiment in FIG. 1 because no moment iscreated. Overall rigidity is ensured because of the use of linearbearings including the guide pins 36 and guide bearings 38.

[0032] While certain exemplary embodiments have been described and shownin the accompanying drawings, it is to be understood that suchembodiments are merely illustrative and not restrictive of the currentinvention, and that this invention is not restricted to the specificconstructions and arrangements shown and described since modificationsmay occur to those ordinarily skilled in the art. Other embodiments aretherefore possible without departing from the scope and spirit of theinvention. One alternative embodiment, for example, may replace theSawyer motor 56 with another horizontal alignment device such as agantry alignment device. A gantry alignment device may include a set ofparallel rails, a third rail and a support component. The set ofparallel rails are secured between two mounting blocks. The third railextends transverse to the set of parallel rails and is secured betweenthe set of parallel rails. The third rail can move along the set ofparallel rails. The support component is secured to the third rail andis movable along its length. Such a device can be used for X-Ypositioning of a substrate.

What is claimed:
 1. Apparatus for electrical testing of a substratehaving a plurality of contact regions, comprising: a frame; a probecard, including a probe card backing member and a plurality of contactregions on the probe card backing member, secured to the frame; atranslation device secured to the frame; an alignment device carried bythe translation device; and a holder, capable of holding the substrate,secured to the alignment device, wherein: (i) the alignment device isoperable to cause alignment movement of the holder past the probe cardso that selected ones of the contact regions are brought into alignmentwith selected ones of the probes; and (ii) the translation device isoperable to cause translation movement, transverse to the alignmentmovement, of the alignment device with the holder towards the probe cardto that a respective one of the contact regions is brought into contactwith a respective contact region.
 2. An apparatus according to claim 1wherein the alignment device is operable to move the holder in at leasta first alignment direction and a second alignment direction transverseto the first alignment direction.
 3. An apparatus according to claim 2wherein the alignment device is operable to rotate the holder about anaxis transverse to a plane of the substrate.
 4. An apparatus accordingto claim 1 wherein the holder and the probe card are rotatable relativeto one another about an axis transverse to a plane of the substrate. 5.An apparatus according to claim 2 wherein the alignment device causesthe alignment movement while the translation device and the probe cardcan remain stationary relative to one another in the alignmentdirections.
 6. An apparatus according to claim 1 wherein the translationdevice includes: a translation stage on which the alignment device islocated; and a load application which is connected between thetranslation stage and the frame and operable to cause the translationalmovement of the translation stage relative to the frame.
 7. An apparatusaccording to claim 6 wherein the translation device includes: at leastone guide bearing; and a respective guide pin in each guide bearing, oneof the guide bearing and the guide pin being secured to the frame andthe other being secured to the translation stage so that the guide pinslides within the guide bearing during the translational movement of thetranslation stage relative to the frame.
 8. Apparatus for electricaltesting of a substrate having a plurality of terminals, comprising: aframe; a probe card, including a probe card backing member and aplurality of contact regions on the probe card backing member, securedto the frame; a translation stage secured to the frame for translationalmovement towards and away from the probe card; a load applicationconnected between the frame and the translation stage so that operationof the load applicator causes the translational movement of thetranslation stage; an alignment stage carried by the translation stagefor alignment movement in a direction transverse to the translationalmovement past the probe card; a positioning actuator providing aconnection between the translation stage and the alignment stage so thatoperation of the positioning actuator causes the alignment movement ofthe alignment stage; and a holder, capable of holding the substrate,located on the alignment stage, wherein: (i) the alignment movementcauses movement of the alignment stage and the holder past the probecard so that selected ones of the contact regions are brought intoalignment with selected ones of the terminals; and (ii) thetranslational movement causes movement of the translation stage, thealignment stage and the holder towards the probe card so that arespective one of the contact regions is brought into contact with arespective contact region of a respective one of the terminals.
 9. Anapparatus according to claim 8 wherein the load applicator is a screwwhich, upon rotation within a thread, causes the translational movement.10. An apparatus according to claim 9 further comprising: at least oneguide bearing; and a respective guide pin in each guide bearing, one ofthe guide bearing and the guide pin being secured to the frame and theother being secured to the translation stage so that the guide pinslides within the guide bearing the translational movement of thetranslation stage relative to the frame.
 11. An apparatus according toclaim 8 wherein the positioning actuator includes at least oneelectromagnet.
 12. An apparatus according to claim 11 wherein thepositioning actuator is part of a Sawyer motor.
 13. An apparatusaccording to claim 8 wherein the holder and the probe card are rotatablerelative to one another, further comprising: a rotation actuator whichrotates the holder and the probe card relative to one another.
 14. Anapparatus according to claim 13 further comprising: a rotation stage onthe alignment stage, the holder being located on the rotation stage andthe rotation stage being rotatable relative to the alignment stage aboutan axis transverse to a plane of the substrate.
 15. An apparatusaccording to claim 14 wherein rotation of the rotation stage bringsselected ones of the contact regions into alignment with selected onesof the terminals.
 16. A method of probing contact regions on asubstrate, comprising: moving a holder located on a translation stage inan alignment direction so that selected ones of the terminals arebrought into alignment with selected ones of contact regions of a probecard; and moving the translation stage in a translation direction sothat a respective one of the contact regions is brought into contactwith a respective contact region of a respective one of the terminals.17. The method of claim 16 wherein the holder holds the substrate.